{"gene":"H2AX","run_date":"2026-06-10T01:55:21","timeline":{"discoveries":[{"year":1998,"finding":"DNA double-strand breaks (DSBs) induce rapid phosphorylation of histone H2AX specifically at serine 139, generating γ-H2AX; approximately 2×10^6 base pairs of chromatin are involved per DSB, indicating large-scale chromatin modification at each break site.","method":"Two-dimensional gel electrophoresis, 32P incorporation, in vivo irradiation of mammalian cells and mice","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct biochemical identification of phosphorylation site by gel analysis and radiolabeling, foundational paper replicated extensively across the field","pmids":["9488723"],"is_preprint":false},{"year":2001,"finding":"ATM is the major kinase responsible for H2AX phosphorylation at serine 139 in response to DSBs in vivo; ATM can phosphorylate H2AX in vitro; DNA-PK contributes residual phosphorylation in ATM-deficient cells, while ATR is not responsible in non-replicating cells.","method":"ATM-/- and DNA-PKcs-/- cell lines/MEFs, in vitro kinase assay, ectopic ATM reconstitution, wortmannin inhibition","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro kinase assay combined with knockout cell lines and reconstitution experiment, replicated by multiple subsequent studies","pmids":["11571274"],"is_preprint":false},{"year":2004,"finding":"ATM and DNA-PK function redundantly to phosphorylate H2AX after ionizing radiation; ablation of both kinases is required to eliminate IR-induced H2AX phosphorylation; ATR is not required for H2AX phosphorylation by DSBs in non-replicating cells; DNA-PK-mediated H2AX phosphorylation contributes to MDC1 and 53BP1 recruitment to DSB sites.","method":"Human fibroblasts and MEFs lacking DNA-PK or ATM, LY294002 inhibition, chicken DT40 double-knockout cells","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple genetic backgrounds and pharmacological inhibition, findings replicated across cell types and organisms","pmids":["15059890"],"is_preprint":false},{"year":2003,"finding":"γ-H2AX is not required for initial recruitment of repair/signaling proteins (Nbs1, 53BP1, Brca1) to DSBs, but is required for their subsequent accumulation and retention into irradiation-induced foci (IRIF); phosphorylation-dead H2AX mutants confirm this distinction.","method":"H2AX-/- cells reconstituted with phosphorylation mutants, immunofluorescence, live-cell imaging","journal":"Nature cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic reconstitution with phosphomutants and direct imaging, clearly separating two mechanistic steps","pmids":["12792649"],"is_preprint":false},{"year":2004,"finding":"The INO80 ATP-dependent chromatin remodeling complex is recruited to DSBs through a direct interaction between the Nhp10 (HMG-like) subunit of INO80 and γ-H2AX (phosphorylated histone H2A in yeast); loss of Nhp10 or γ-H2AX reduces INO80 recruitment; INO80 components show synthetic genetic interactions with the RAD52 repair pathway.","method":"Co-immunoprecipitation, chromatin immunoprecipitation at HO endonuclease-induced DSB in yeast, genetic epistasis","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct biochemical interaction plus ChIP at defined DSB plus genetic epistasis, multiple orthogonal methods","pmids":["15607974"],"is_preprint":false},{"year":2005,"finding":"Protein phosphatase 2A (PP2A) catalytic subunit directly dephosphorylates γ-H2AX in vitro, co-immunoprecipitates and co-localizes with γ-H2AX in DNA damage foci; PP2A recruitment to foci is H2AX-dependent; PP2A inhibition/knockdown causes γ-H2AX foci persistence, inefficient DNA repair, and hypersensitivity to DNA damage.","method":"Co-immunoprecipitation, in vitro phosphatase assay, RNAi knockdown, immunofluorescence colocalization","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro dephosphorylation assay combined with Co-IP and functional RNAi rescue, multiple orthogonal methods in one study","pmids":["16310392"],"is_preprint":false},{"year":2008,"finding":"A PP4 phosphatase complex (PP4C/PP4R2/PP4R3β) specifically dephosphorylates ATR-mediated γ-H2AX generated during DNA replication, acting directly on γ-H2AX within mononucleosomes in vitro; PP4 silencing causes persistence of replication-associated γ-H2AX foci and hypersensitivity to replication inhibitors but not radiomimetic drugs, indicating pathway specificity distinct from PP2A.","method":"In vitro phosphatase assay with mononucleosomes, RNAi knockdown, clonogenic survival, immunofluorescence","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with mononucleosome substrate plus RNAi functional analysis with specific pathway controls","pmids":["18614045"],"is_preprint":false},{"year":2009,"finding":"EYA protein tyrosine phosphatase dephosphorylates a C-terminal tyrosine (Y142) of H2AX in response to genotoxic stress; when Y142 is phosphorylated, pro-apoptotic factors are recruited to the γ-H2AX tail; EYA-mediated dephosphorylation of Y142 shifts the balance toward DNA repair factor recruitment rather than apoptosis.","method":"In vitro phosphatase assay, mutation of Y142, co-immunoprecipitation, mammalian cell genotoxic stress assays","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro enzymatic assay with mutagenesis and demonstration of functional outcome (repair vs. apoptosis factor recruitment)","pmids":["19234442"],"is_preprint":false},{"year":2007,"finding":"TIP60 histone acetyltransferase acetylates H2AX following ionizing radiation, which then promotes ubiquitination of H2AX via the ubiquitin-conjugating enzyme UBC13; this TIP60-UBC13-dependent acetylation-then-ubiquitination is required for H2AX release from damaged chromatin, enhancing histone dynamics during DNA damage response.","method":"Ionizing radiation treatment of human cells, in vitro acetylation and ubiquitination assays, immunoprecipitation, chromatin fractionation","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro enzymatic assays for both acetylation and ubiquitination, showing sequential modification and functional consequence (chromatin release)","pmids":["17709392"],"is_preprint":false},{"year":2008,"finding":"FACT complex (Spt16/SSRP1) is an H2AX-associated factor that mediates exchange of H2AX with conventional H2A within nucleosomes; DNA-PK-mediated phosphorylation of H2AX facilitates this exchange by inducing nucleosomal conformational changes; PARP1-mediated poly-ADP-ribosylation of Spt16 inhibits FACT-dependent H2AX exchange.","method":"Purification of H2AX-associated factors, in vitro nucleosome exchange assay, DNA-PK and PARP1 activity assays","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Moderate — biochemical reconstitution of exchange reaction with purified factors, in vitro activity assays showing regulatory modifications","pmids":["18406329"],"is_preprint":false},{"year":2006,"finding":"H2AX phosphorylation (γ-H2AX) is required for DNA ladder formation during apoptosis but not for caspase-3 activation; JNK (activated by UVA) phosphorylates H2AX; H2AX phosphorylation is critical for DNA degradation by caspase-activated DNase (CAD) in vitro; H2AX-/- MEFs lack DNA fragmentation despite normal caspase-3/CAD activation.","method":"H2AX knockout MEFs, in vitro CAD-mediated DNA degradation assay, immunofluorescence, caspase activity assays","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution of CAD-mediated DNA degradation combined with genetic knockout, multiple orthogonal methods","pmids":["16818236"],"is_preprint":false},{"year":2006,"finding":"DNA-PK is solely responsible for H2AX phosphorylation during apoptotic DNA fragmentation, while ATM is dispensable; DNA-PKcs autophosphorylation at S2056 precedes γ-H2AX induction in apoptosis; ATM is proteolytically degraded before DNA fragmentation, leaving DNA-PK as the predominant kinase in late apoptosis.","method":"ATM-/- and DNA-PKcs-/- cell lines, pharmacological kinase inhibition, immunoblotting for autophosphorylation, immunofluorescence in apoptotic vs non-apoptotic nuclei","journal":"DNA repair","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple genetic knockouts combined with pharmacological inhibition and biochemical characterization across cell types","pmids":["16567133"],"is_preprint":false},{"year":2003,"finding":"DNA-PK can be activated by nucleosomes (via Ku binding to ends of nucleosomal DNA) and phosphorylates H2AX within nucleosomes; histone acetylation enhances H2AX phosphorylation by DNA-PK specifically when H2AX is nucleosome-associated but not in free form.","method":"In vitro kinase assay with reconstituted nucleosomes, DNA-PK activation assay, acetylated vs non-acetylated nucleosome substrates","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with defined nucleosomal substrates, multiple modification states tested","pmids":["14627815"],"is_preprint":false},{"year":2003,"finding":"H2AX is required for the accumulation of Nbs1, 53BP1, Brca1, and other factors into IRIF; loss of a single H2AX allele compromises genomic integrity; restoration with wild-type H2AX rescues genomic stability and radiation resistance, but substitution of the conserved serine phosphorylation site (S→A or S→E) abolishes this rescue, establishing that serine phosphorylation is functionally essential.","method":"H2AX heterozygous and homozygous null mice, gene rescue with phosphorylation-site mutants, tumor analysis, cytogenetics","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo genetic rescue with phosphomutants demonstrating mechanistic requirement, complemented by genomic instability readouts","pmids":["12914701"],"is_preprint":false},{"year":2010,"finding":"Wip1 (wild-type p53-induced phosphatase 1) directly dephosphorylates γ-H2AX in vitro and in vivo; ectopic Wip1 expression prematurely removes γ-H2AX, disrupts repair factor recruitment to damage sites, and delays DNA repair; Wip1 deletion enhances γ-H2AX in cells under oncogenic stress.","method":"In vitro phosphatase assay, ectopic expression, Wip1 deletion cells, immunofluorescence of repair foci","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct in vitro dephosphorylation plus genetic gain- and loss-of-function with functional repair readout","pmids":["20460517"],"is_preprint":false},{"year":2011,"finding":"Monoubiquitination of H2AX at Lys119/Lys120 by the RNF2-BMI1 E3 ligase complex is required for efficient γ-H2AX formation and ATM recruitment to DSBs; H2AX K120R mutation (abolishing monoubiquitination) impairs p-ATM recruitment, reduces γ-H2AX and MDC1 accumulation at DSBs, and impairs NBS1 and CHK2 activation; the regulatory effect of RNF2-BMI1 on γ-H2AX is ATM-dependent.","method":"Site-directed mutagenesis of H2AX (K119/120R), RNF2-BMI1 Co-IP, siRNA knockdown, immunofluorescence foci analysis, ionizing radiation","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — mutagenesis of ubiquitination sites combined with Co-IP and functional rescue, multiple downstream pathway readouts","pmids":["21676867"],"is_preprint":false},{"year":2014,"finding":"SUV39H2 histone methyltransferase methylates H2AX on lysine 134; mutation of K134 significantly reduces γ-H2AX levels; Suv39h2 knockout or knockdown reduces γ-H2AX after DSB induction; K134 methylation positively correlates with γ-H2AX levels in clinical tissue samples.","method":"In vitro methyltransferase assay, H2AX K134 mutagenesis, Suv39h2 KO cells, tissue microarray, clonogenic survival","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro enzymatic assay with mutagenesis and genetic knockout, replicated in clinical tissue samples","pmids":["25487737"],"is_preprint":false},{"year":2004,"finding":"BRCA1 is required to recruit ATR to XY chromatin at the onset of meiotic sex chromosome inactivation (MSCI); ATR then phosphorylates H2AX on the sex chromosomes; in BRCA1-mutant pachytene cells, ATR mislocalizes and phosphorylates H2AX at aberrant autossomal sites, causing MSCI failure; rare cells where ATR correctly localizes to XY chromatin show H2AX phosphorylation and successful MSCI.","method":"Immunofluorescence colocalization in spermatocytes from BRCA1-mutant mice, co-staining of ATR and γH2AX","journal":"Current biology : CB","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic model with mechanistic pathway placement (BRCA1→ATR→γH2AX→MSCI) demonstrated in vivo in multiple experimental conditions","pmids":["15589157"],"is_preprint":false},{"year":2007,"finding":"Phosphorylated H2AX (γH2AX) is required for FANCD2 recruitment to chromatin at stalled replication forks; FANCD2 binding to γH2AX is BRCA1-dependent; H2AX-deficient cells display an FA-like phenotype including excess chromatid-type aberrations and MMC hypersensitivity; this hypersensitivity is not increased by additional FANCD2 depletion, placing H2AX and FANCD2 in the same pathway.","method":"H2AX knockout mouse cells, non-phosphorylable H2AX mutant (S136A/S139A), MMC sensitivity, chromatin fractionation, immunofluorescence, genetic epistasis by double depletion","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis by double depletion/knockout, phosphomutant cells, multiple orthogonal phenotypic readouts","pmids":["17304220"],"is_preprint":false},{"year":2009,"finding":"ATM and H2AX have complementary functions; combined ATM/H2AX deficiency causes embryonic lethality and dramatic genomic instability; severe instability in double-deficient cells is associated with a requirement for H2AX in repairing oxidative DNA damage that accumulates due to ATM deficiency.","method":"ATM/H2AX double-knockout mice and MEFs, genomic instability assays, embryonic lethality analysis","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic double-knockout with in vivo epistasis revealing synergistic interaction and mechanistic basis","pmids":["18599436"],"is_preprint":false},{"year":2008,"finding":"H2AX is required for endothelial cell proliferation under hypoxic conditions; hypoxia induces replication-associated γ-H2AX in endothelial cells; H2AX deficiency reduces hypoxia-driven neovascularization in pathologic proliferative retinopathy, hind-limb ischemia, and tumor angiogenesis; endothelial-specific H2afx deletion recapitulates this phenotype.","method":"H2afx-/- mice, endothelial-specific conditional knockout, in vitro hypoxic cell proliferation assays, retinal neovascularization and tumor angiogenesis models","journal":"Nature medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — global and cell-type-specific genetic deletion with in vivo neovascularization phenotypes and in vitro mechanistic validation","pmids":["19377486"],"is_preprint":false},{"year":2009,"finding":"H2AX is required for p21-dependent cell cycle arrest after replication stalling; in H2AX-deficient cells, p21 undergoes proteasome-dependent degradation after stalled replication, leading to mitotic catastrophe; H2AX-proficient cells increase p21 levels and arrest the cell cycle; this establishes H2AX as a component of the p53/p21 cell cycle checkpoint pathway.","method":"H2AX-/- cells and RNAi knockdown, AAV-induced stalled replication, flow cytometry, proteasome inhibitor rescue, H2AX complementation","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic and RNAi-based loss-of-function with complementation, defined molecular mechanism involving p21 stabilization","pmids":["19273588"],"is_preprint":false},{"year":2010,"finding":"H2AX prevents CtIP-mediated DNA end resection of hairpin-sealed coding ends in G1-phase lymphocytes; γ-H2AX and its reader MDC1 inhibit CtIP access; ATM activates antagonistic pathways modulating this resection; in H2AX-deficient cells, CtIP promotes aberrant hairpin opening, leading to microhomology-mediated joins and chromosomal deletions.","method":"H2AX-/- murine lymphocytes, RAG endonuclease-generated DSB analysis, CtIP knockdown epistasis, sequencing of joins, chromosomal deletion analysis","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo genetic epistasis with CtIP and MDC1, sequencing-based characterization of repair outcomes, mechanistic pathway defined","pmids":["21160476"],"is_preprint":false},{"year":2012,"finding":"H2AX increases ROS generation after DNA damage through the Nox1/Rac1 pathway; H2AX overexpression alone induces ROS; H2AX reduces interaction between Nox1 activator NOXA1 and its inhibitor 14-3-3ζ, thereby increasing Nox1 activity; Nox1 knockdown or Rac1N17 expression reduces H2AX-mediated ROS and cell death.","method":"H2AX overexpression/knockdown, Nox1/Nox4 siRNA, Rac1 dominant-negative expression, ROS measurement, co-immunoprecipitation of NOXA1/14-3-3ζ","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple genetic interventions and Co-IP showing mechanism, but single-laboratory study with no reconstitution","pmids":["22237206"],"is_preprint":false},{"year":2012,"finding":"In MNNG-induced caspase-independent necroptosis, ATM and DNA-PK phosphorylate H2AX at S139 in a synergistic but temporally distinct manner (ATM early, DNA-PK later); γH2AX associates with AIF and CypA to form a DNA-degrading complex; H2AX S139A mutation or H2AX ablation abolishes chromatinolysis and necroptosis; phosphomimetic H2AX S139E rescues necroptosis in H2AX-/- cells.","method":"H2AX-/- cells, S139A/S139E mutant reconstitution, ATM/DNA-PK knockout and pharmacological inhibition, AIF co-immunoprecipitation","journal":"Cell death & disease","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout plus phosphomimetic/phospho-dead rescue, multiple kinase genetic/pharmacological interventions, mechanistic complex identified","pmids":["22972376"],"is_preprint":false},{"year":2014,"finding":"Dub3 ubiquitin hydrolase deubiquitinates H2AX; Dub3 directly interacts with H2AX and deubiquitinates it in vitro; Dub3 overexpression decreases DSB-induced H2AX monoubiquitination and abrogates 53BP1 and BRCA1 focus formation (but not MDC1/γH2AX foci); Dub3 counteracts RNF8 and RNF168 E3 ligases; Dub3 depletion accelerates H2AX dephosphorylation at later time points.","method":"In vitro deubiquitination assay, Co-immunoprecipitation, RNF8/RNF168 counter-assay, immunofluorescence foci analysis, catalytic dead mutant","journal":"Molecular oncology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro deubiquitination assay with Co-IP and functional foci readout, catalytic-dead controls","pmids":["24704006"],"is_preprint":false},{"year":2016,"finding":"Chronic oxidative stress reduces H2AX protein levels via enhanced interaction with E3 ubiquitin ligase RNF168, leading to H2AX poly-ubiquitination and proteasomal degradation; deficient JunD/Nrf2 antioxidant response drives ROS accumulation and H2AX destabilization.","method":"Co-immunoprecipitation of H2AX and RNF168, ubiquitination assays, proteasome inhibitor rescue, JunD/Nrf2 manipulation, breast cancer cell lines and patient samples","journal":"EMBO molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP and ubiquitination assays identifying mechanism, single-lab study with multiple methods","pmids":["27006338"],"is_preprint":false},{"year":2019,"finding":"PRMT5 sustains RNF168 expression, which stabilizes H2AX protein; in the absence of RNF168 (due to PRMT5 suppression in MTAP-deficient cells), the E3 ubiquitin ligase SMURF2 destabilizes H2AX; RNF168 and SMURF2 dynamically interact with H2AX acting as stabilizer and destabilizer respectively, defining a PRMT5-RNF168-SMURF2 cascade controlling H2AX proteostasis.","method":"PRMT5/RNF168/SMURF2 knockdown and overexpression, Co-IP, ubiquitination assays, MTAP-deficient glioblastoma cell models","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP and functional knockdown in multiple cell contexts, single-laboratory study","pmids":["31533041"],"is_preprint":false},{"year":2020,"finding":"H2AX glutamate 141 (E141) is ADP-ribosylated following oxidative DNA damage; this modification mediates recruitment of Neil3 glycosylase to DNA damage sites for base excision repair (BER); ADP-ribosylation-deficient H2AX E141A mutant enhances γH2AX (S139 phosphorylation) and erroneously accumulates DSB response factors at BER sites.","method":"Unbiased mass spectrometry identification of ADP-ribosylation site, E141A mutagenesis, Neil3 recruitment assays, comparison of BER vs DSB response factors","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — mass spectrometry identification of novel modification site combined with mutagenesis and functional recruitment assay","pmids":["33264433"],"is_preprint":false},{"year":2023,"finding":"SIRT1 deacetylates H2AX at Lys5, and this deacetylation is required for efficient Ser139 phosphorylation of H2AX; SIRT1 knockdown increases acetyl-Lys5-H2AX and blunts γ-H2AX formation; H2AX K5Q (acetylation mimic) mutant shows reduced Ser139 phosphorylation in response to doxorubicin; K5Q and S139A mutants both enhance caspase-3 activation, demonstrating functional consequence of SIRT1-H2AX axis.","method":"Cardiomyocyte-specific Sirt1 conditional knockout mice, SIRT1 knockdown/overexpression in H9c2 cells, K5Q mutant H2AX, immunostaining for acetyl-K5 and phospho-S139 H2AX, caspase-3 assay","journal":"Cardiovascular research","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo conditional knockout combined with mutagenesis of both modification sites and functional rescue, multiple orthogonal methods","pmids":["35258628"],"is_preprint":false},{"year":2015,"finding":"H2AX controls double-strand break repair by homologous recombination (HR) between sister chromatids through interaction of γ-H2AX with the chromatin-associated adaptor protein MDC1; mass spectrometry identified novel IR-responsive post-translationally modified residues of H2AX beyond S139; HR and IR-resistance functions of H2AX are controlled largely by MDC1-interacting residues, with additional H2AX residues modulating these functions.","method":"Mass spectrometry of IR-treated cells, mutagenesis of H2AX residues, HR assay (sister chromatid recombination), clonogenic survival","journal":"Cell cycle (Georgetown, Tex.)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mass spectrometry identification plus mutagenesis functional analysis, single-laboratory study","pmids":["20703100"],"is_preprint":false},{"year":2008,"finding":"ATR deficiency leads to H2AX phosphorylation by ATM and DNA-PKcs at collapsed replication forks; increased Rad51 focal accumulation in ATR-deficient cells is largely H2AX-dependent; dual deficiency of ATR and H2AX causes synergistic increases in chromatid breaks; H2AX S139 (the ATM/DNA-PK phosphorylation site) is required for genome stabilization in the absence of ATR.","method":"ATR-deficient and H2AX-deficient cells, S139A H2AX mutant, cytogenetic analysis, Rad51 immunofluorescence, genetic double-deficiency","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic double-deficiency with phosphosite mutagenesis demonstrating epistasis and mechanism, synergistic cytogenetic phenotype","pmids":["19049966"],"is_preprint":false},{"year":2005,"finding":"ATM-dependent H2AX phosphorylation occurs during mitosis in normally growing mammalian cells independently of exogenous DNA damage; two distinct γ-H2AX focal populations exist in unirradiated cells: large amorphous foci colocalizing with DSB repair proteins and smaller foci that do not recruit DSB repair factors; the mitotic γ-H2AX phosphorylation may contribute to fidelity of mitosis independent of DNA damage.","method":"Quantitative in situ immunofluorescence, cell cycle analysis, ATM-inhibitor treatment, multiple unirradiated mammalian cell lines","journal":"Molecular biology of the cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — quantitative imaging with ATM inhibition providing mechanistic attribution, single-laboratory study","pmids":["16030261"],"is_preprint":false},{"year":2020,"finding":"Chromosomal contacts (topological structure) of a DSB site are the primary determinants of γH2AX domain landscapes; DSBs that disrupt a topological border allow γH2AX extension into both adjacent compartments; DSBs near a border produce highly asymmetric γH2AX domains with γH2AX nearly absent from one broken end.","method":"Hi-C chromosome conformation capture combined with γH2AX ChIP-seq at specific DSB sites","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — genome-wide chromatin conformation combined with DSB-specific γH2AX mapping, mechanistic link between TAD structure and γH2AX spreading","pmids":["32572033"],"is_preprint":false},{"year":2015,"finding":"VRK1 kinase directly phosphorylates H2AX at Ser139 in response to ionizing radiation; VRK1 stably interacts with H2AX and H3 under basal conditions; VRK1 depletion prevents γH2AX foci formation and reduces H3/H4 acetylation required for chromatin relaxation after DNA damage; kinase-active but not kinase-dead VRK1 rescues γH2AX foci formation.","method":"In vitro kinase assay with nucleosomal substrate, co-immunoprecipitation, VRK1 depletion/rescue with kinase-dead mutant, immunofluorescence","journal":"Epigenetics","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro kinase assay combined with kinase-dead mutant rescue and Co-IP, direct demonstration of VRK1 as H2AX kinase","pmids":["25923214"],"is_preprint":false},{"year":2003,"finding":"H2AX regulates telomere clustering during meiotic prophase I; H2AX is dispensable for mitotic telomere maintenance and for chromosome fusions from critically shortened or deprotected telomeres; H2AX is required downstream of ATM for proper topological distribution of telomeres during meiosis.","method":"H2AX-/- mice, meiotic spread immunofluorescence, telomere FISH, ATM inhibitor treatment","journal":"The Journal of cell biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic knockout with specific meiotic and mitotic readouts, ATM pathway placement, single-laboratory study","pmids":["14530383"],"is_preprint":false},{"year":2021,"finding":"HMGA2 induces DNA nicks at transcription start sites, which triggers FACT complex to incorporate H2AX-containing nucleosomes; phosphorylation of H2AX at S139 (γH2AX) is then required for repair-mediated DNA demethylation and transcription activation in the context of TGFB1 signaling.","method":"HMGA2 manipulation, H2AX S139 mutation, FACT complex assays, DNA methylation analysis, transcription start site occupancy","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple molecular interventions linking HMGA2-FACT-H2AX pathway to transcription, but single-laboratory study with complex multi-step mechanism","pmids":["33594057"],"is_preprint":false},{"year":2015,"finding":"Phosphorylated H2AFX (γH2AFX) on asynapsed chromosomes during meiotic prophase I triggers oocyte elimination at diplonema in mice with chromosome abnormalities (XO and translocations); deletion or point mutation of H2afx restores oocyte numbers in XO females to wild-type (XX) levels, establishing γH2AFX as a causal mediator of oocyte elimination.","method":"H2afx knockout and point mutant mice (XO background), oocyte counting, γH2AFX immunostaining, chromosomal asynapsis analysis","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic rescue by H2afx deletion and point mutation in defined chromosomal abnormality model, direct causal demonstration","pmids":["26509888"],"is_preprint":false},{"year":2018,"finding":"MOF histone acetyltransferase (which generates H4K16ac) is required for the chromatin-wide expansion of all three waves of H2AX phosphorylation during male meiotic prophase I; without MOF, γH2AX signals are restricted to chromosomal axes and fail to expand to broad chromatin domains; MSCI fails in ~40% of Mof cKO pachytene cells; MOF facilitates meiotic DSB repair after RAD51 recruitment.","method":"Germ cell-specific Mof conditional knockout mice (Stra8-Cre), γH2AX immunostaining, MDC1 colocalization, RAD51 recruitment assay, crossover analysis","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo conditional knockout with multiple mechanistic readouts (γH2AX spreading, MSCI, DSB repair), defining MOF as regulator of H2AX phosphorylation expansion","pmids":["29795555"],"is_preprint":false},{"year":2020,"finding":"UBE2T-RNF8 acts as an E2-E3 pair that monoubiquitinates H2AX/γH2AX at K119/K120 upon radiation exposure; this monoubiquitination facilitates CHK1 phosphorylation/activation and promotes CHK1 release from chromatin; mutations in UBE2T (C86A, E2-dead) or H2AX (K119/120R) abolish CHK1 activation; CHK1 inhibition impairs UBE2T-mediated radioresistance.","method":"Co-IP of UBE2T with H2AX, K119/120R H2AX mutant, C86A UBE2T mutant, CHK1 chromatin fractionation, clonogenic survival, xenograft models","journal":"Journal of experimental & clinical cancer research : CR","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mutagenesis and Co-IP with functional pathway analysis, single-laboratory study","pmids":["33087136"],"is_preprint":false}],"current_model":"H2AX is a histone H2A variant that, upon DNA double-strand break (DSB) formation, is rapidly phosphorylated at serine 139 (generating γ-H2AX) primarily by ATM (with redundant contributions from DNA-PK and, during replication stress, ATR and VRK1); γ-H2AX spreads over megabase chromatin domains—shaped by topological domain boundaries—and serves as a docking platform that concentrates (but is not required for initial recruitment of) DSB repair and signaling factors including MDC1, 53BP1, NBS1, and BRCA1; the modification is reversed by PP2A (at DSBs), PP4 (at replication-associated breaks), and Wip1; H2AX also undergoes additional post-translational modifications—including acetylation at K5 by TIP60 (promoting ubiquitination) and deacetylation by SIRT1 (promoting S139 phosphorylation), monoubiquitination at K119/120 by RNF2-BMI1/UBE2T-RNF8/RNF168 (counteracted by Dub3), ADP-ribosylation at E141 (for base excision repair and Neil3 recruitment), and methylation at K134 by SUV39H2 (supporting γ-H2AX formation)—that together regulate chromatin dynamics, repair factor exchange via FACT, and protein stability via PRMT5-RNF168-SMURF2; beyond DSB repair, γ-H2AX determines life/death fate via Y142 phosphorylation (directing either repair or apoptotic factor binding), participates in caspase-independent necroptosis (forming a DNA-degrading complex with AIF/CypA), is required for DNA ladder formation during apoptosis (via JNK phosphorylation enabling CAD activity), supports FANCD2 recruitment at stalled forks within the FA/BRCA pathway, activates cell cycle arrest through the p53/p21 axis, mediates meiotic sex chromosome inactivation (via ATR/BRCA1 recruitment to XY chromatin), controls meiotic telomere clustering and oocyte elimination at asynapsis, and is required for endothelial cell proliferation under hypoxia driving neovascularization."},"narrative":{"mechanistic_narrative":"H2AX is a histone H2A variant that functions as the central chromatin sensor of DNA double-strand breaks (DSBs): break formation triggers rapid phosphorylation of its C-terminal Ser139 to generate γ-H2AX, marking large (~2×10^6 bp) chromatin domains around each lesion [PMID:9488723]. This phosphorylation is executed primarily by ATM, with DNA-PK acting redundantly to ensure that loss of both kinases is required to eliminate the IR-induced signal [PMID:11571274, PMID:15059890], while VRK1 also directly phosphorylates Ser139 and supports chromatin relaxation after damage [PMID:25923214]. γ-H2AX is not needed for the initial recruitment of repair/signaling factors but is required for their stable accumulation and retention in irradiation-induced foci, including NBS1, 53BP1 and BRCA1 [PMID:12792649], and genetic rescue with a Ser-to-Ala/Glu mutant fails to restore genomic stability, establishing Ser139 phosphorylation as functionally essential [PMID:12914701]. The mark spreads across chromatin in a manner dictated by topological domain boundaries [PMID:32572033] and acts through the reader MDC1 to direct homologous recombination between sister chromatids [PMID:20703100], to protect coding-end hairpins from CtIP-mediated resection [PMID:21160476], and to recruit FANCD2 at stalled forks within the FA/BRCA pathway [PMID:17304220]; in the absence of ATR, ATM/DNA-PK-dependent Ser139 phosphorylation stabilizes collapsed replication forks [PMID:19049966]. The signal is reversed by distinct phosphatases acting on different lesion contexts: PP2A at DSBs [PMID:16310392], the PP4C/PP4R2/PP4R3β complex at replication-associated breaks [PMID:18614045], Wip1 to terminate the response [PMID:20460517], and EYA, which dephosphorylates the C-terminal Tyr142 to shift γ-H2AX from apoptotic to repair-factor binding [PMID:19234442]. Beyond phosphorylation, H2AX is regulated by an extensive modification network: TIP60-UBC13 acetylation-then-ubiquitination drives H2AX release from chromatin [PMID:17709392], FACT mediates H2AX/H2A nucleosome exchange in a phosphorylation- and PARP1-regulated manner [PMID:18406329], SIRT1 deacetylates Lys5 to permit Ser139 phosphorylation [PMID:35258628], RNF2-BMI1 monoubiquitination at K119/120 and SUV39H2 methylation at K134 promote γ-H2AX formation [PMID:21676867, PMID:25487737], UBE2T-RNF8 monoubiquitination links γ-H2AX to CHK1 activation [PMID:33087136], ADP-ribosylation at Glu141 directs Neil3 recruitment for base excision repair [PMID:33264433], and a PRMT5-RNF168-SMURF2 axis with the deubiquitinase Dub3 governs H2AX proteostasis and repair-factor focus formation [PMID:24704006, PMID:31533041]. H2AX activity extends beyond repair to cell-fate decisions, being required for p21-dependent cell-cycle arrest [PMID:19273588], DNA-ladder formation during apoptosis via JNK and CAD [PMID:16818236], and assembly of an AIF/CypA DNA-degrading complex in caspase-independent necroptosis [PMID:22972376]. In the germline, H2AX phosphorylation mediates meiotic sex chromosome inactivation downstream of BRCA1/ATR [PMID:15589157], controls meiotic telomere clustering [PMID:14530383], and drives oocyte elimination at asynapsis [PMID:26509888], with MOF-dependent H4K16 acetylation enabling chromatin-wide γ-H2AX spreading in meiosis [PMID:29795555]; it is additionally required for hypoxia-driven endothelial proliferation and neovascularization [PMID:19377486].","teleology":[{"year":1998,"claim":"Established that DSBs are physically signaled in chromatin by a specific histone modification, defining γ-H2AX as a megabase-scale break marker.","evidence":"2D gel electrophoresis with 32P incorporation after in vivo irradiation of mammalian cells and mice","pmids":["9488723"],"confidence":"High","gaps":["Did not identify the responsible kinase","Did not establish the functional consequence of the modification"]},{"year":2001,"claim":"Identified ATM as the major Ser139 kinase with DNA-PK as a backup, answering which signaling kinase couples break detection to the chromatin mark.","evidence":"ATM-/- and DNA-PKcs-/- cells, in vitro kinase assay, reconstitution and wortmannin inhibition","pmids":["11571274"],"confidence":"High","gaps":["Relative contribution of each kinase at different lesion types not fully resolved","Did not address replication-stress kinases"]},{"year":2003,"claim":"Distinguished initial factor recruitment from stable focus accumulation, showing γ-H2AX is a retention/amplification platform rather than the primary recruitment signal.","evidence":"H2AX-/- cells reconstituted with phosphomutants, immunofluorescence and live imaging; phosphomutant rescue in null mice","pmids":["12792649","12914701"],"confidence":"High","gaps":["Mechanism by which retained factors execute repair not defined","Reader proteins bridging γ-H2AX to factors not yet identified"]},{"year":2004,"claim":"Connected γ-H2AX to chromatin remodeling by showing direct recruitment of the INO80 complex, beginning the mechanistic picture of how the mark reshapes chromatin at breaks.","evidence":"Co-IP, ChIP at HO-induced DSB and genetic epistasis in yeast","pmids":["15607974"],"confidence":"High","gaps":["Conservation of the Nhp10-γH2A interaction to mammals not established here","Functional outcome of remodeling on repair pathway choice unresolved"]},{"year":2004,"claim":"Resolved kinase redundancy by showing combined ATM/DNA-PK loss is required to abolish IR-induced phosphorylation and that DNA-PK contributes to MDC1/53BP1 recruitment.","evidence":"Human fibroblasts/MEFs lacking ATM or DNA-PK, LY294002 inhibition, DT40 double-knockouts","pmids":["15059890"],"confidence":"High","gaps":["Did not address ATR contribution during replication","Spatial division of labor between kinases at a single break not mapped"]},{"year":2005,"claim":"Identified PP2A as the DSB-associated eraser, establishing that the γ-H2AX signal is actively reversed to permit repair completion.","evidence":"In vitro phosphatase assay, Co-IP, colocalization and RNAi with repair/survival readouts","pmids":["16310392"],"confidence":"High","gaps":["Did not distinguish lesion-context specificity from other phosphatases","Regulation of PP2A recruitment timing unresolved"]},{"year":2003,"claim":"Showed DNA-PK can be activated by and phosphorylate H2AX within nucleosomes, and that acetylation enhances this only in the nucleosomal context, linking chromatin state to mark deposition.","evidence":"In vitro kinase assays with reconstituted, acetylated/non-acetylated nucleosomes","pmids":["14627815"],"confidence":"High","gaps":["In vivo relevance of acetylation-stimulated phosphorylation not tested here","Identity of the acetyltransferase not addressed"]},{"year":2006,"claim":"Defined a repair-independent role for γ-H2AX in apoptotic DNA fragmentation, showing it is required for CAD-mediated DNA laddering downstream of JNK.","evidence":"H2AX-/- MEFs, in vitro CAD degradation assay, caspase activity assays","pmids":["16818236"],"confidence":"High","gaps":["How γ-H2AX enables CAD access to DNA not structurally defined","Generality across apoptotic stimuli not fully tested"]},{"year":2006,"claim":"Showed that in late apoptosis DNA-PK, not ATM (which is degraded), drives γ-H2AX, refining kinase usage by cellular context.","evidence":"ATM-/- and DNA-PKcs-/- cells, kinase inhibition, autophosphorylation immunoblot","pmids":["16567133"],"confidence":"High","gaps":["Trigger for DNA-PK activation in apoptotic chromatin not defined","Link to the CAD fragmentation step not mechanistically bridged"]},{"year":2007,"claim":"Placed H2AX in the FA/BRCA pathway by showing γ-H2AX is required for BRCA1-dependent FANCD2 recruitment at stalled forks, extending its role to replication stress.","evidence":"H2AX-null cells, phosphomutant, MMC sensitivity, chromatin fractionation and double-depletion epistasis","pmids":["17304220"],"confidence":"High","gaps":["Direct physical γH2AX-FANCD2 contact vs indirect not resolved","Reader linking γ-H2AX to FANCD2 not identified"]},{"year":2007,"claim":"Established acetylation-coupled ubiquitination by TIP60-UBC13 as the mechanism for H2AX release from damaged chromatin, adding histone dynamics to the response.","evidence":"In vitro acetylation and ubiquitination assays, chromatin fractionation after IR","pmids":["17709392"],"confidence":"High","gaps":["Acetylated lysine residue not specified here","Downstream fate of released H2AX not tracked"]},{"year":2008,"claim":"Identified the FACT complex as the machine that exchanges H2AX in nucleosomes, with phosphorylation promoting and PARP1-ribosylation inhibiting exchange, defining mark turnover dynamics.","evidence":"Purification of H2AX-associated factors, in vitro nucleosome exchange, DNA-PK and PARP1 activity assays","pmids":["18406329"],"confidence":"High","gaps":["In vivo contribution of FACT exchange to repair outcome not quantified","Coordination with INO80 remodeling not addressed"]},{"year":2008,"claim":"Defined a replication-specific eraser, the PP4C/PP4R2/PP4R3β complex, distinguishing erasure of ATR-generated γ-H2AX from PP2A action at DSBs.","evidence":"In vitro phosphatase assay on mononucleosomes, RNAi, clonogenic survival with pathway-specific drugs","pmids":["18614045"],"confidence":"High","gaps":["Recruitment mechanism of PP4 to replication foci unresolved","Crosstalk with PP2A/Wip1 not mapped"]},{"year":2008,"claim":"Demonstrated that H2AX stabilizes collapsed forks in ATR-deficient cells via ATM/DNA-PK Ser139 phosphorylation, integrating H2AX into the replication-stress response.","evidence":"ATR/H2AX double-deficient cells, S139A mutant, cytogenetics, Rad51 immunofluorescence","pmids":["19049966"],"confidence":"High","gaps":["How γ-H2AX promotes Rad51 loading mechanistically unresolved","Direct vs indirect fork protection not distinguished"]},{"year":2009,"claim":"Revealed a checkpoint role by showing H2AX is required to stabilize p21 and enforce cell-cycle arrest after replication stalling, preventing mitotic catastrophe.","evidence":"H2AX-/- cells and RNAi, AAV-induced stalling, flow cytometry, proteasome rescue, complementation","pmids":["19273588"],"confidence":"High","gaps":["Molecular link from γ-H2AX chromatin to p21 stabilization not defined","Role of p53 upstream of p21 in this context not dissected"]},{"year":2009,"claim":"Showed ATM and H2AX have complementary essential roles, with H2AX required to repair oxidative damage accumulating in ATM deficiency, explaining their synthetic lethality.","evidence":"ATM/H2AX double-knockout mice and MEFs, genomic instability and embryonic lethality analysis","pmids":["18599436"],"confidence":"High","gaps":["Direct biochemical role of H2AX in oxidative damage repair not defined","Pathway connecting H2AX to oxidative lesion repair unresolved"]},{"year":2009,"claim":"Uncovered a life/death switch at the C-terminal tail, where EYA dephosphorylation of Tyr142 biases between apoptotic and repair factor binding to γ-H2AX.","evidence":"In vitro phosphatase assay, Y142 mutagenesis, Co-IP, genotoxic stress assays","pmids":["19234442"],"confidence":"High","gaps":["Identity of the Y142 kinase not addressed here","Specific apoptotic factors recruited not fully enumerated"]},{"year":2010,"claim":"Added Wip1 as a phosphatase that terminates the γ-H2AX response, linking the mark's erasure to oncogenic-stress regulation.","evidence":"In vitro phosphatase assay, ectopic expression and Wip1 deletion, repair foci imaging","pmids":["20460517"],"confidence":"High","gaps":["Lesion-context specificity relative to PP2A/PP4 not defined","Recruitment of Wip1 to foci not characterized"]},{"year":2010,"claim":"Established MDC1-interacting residues of H2AX as the principal determinant of sister-chromatid HR and IR resistance, mapping the reader-dependent output of the mark.","evidence":"Mass spectrometry of IR-treated cells, H2AX residue mutagenesis, HR and clonogenic assays","pmids":["20703100"],"confidence":"Medium","gaps":["Single-laboratory study without independent replication","Functions of additional modified residues only partially defined"]},{"year":2010,"claim":"Showed γ-H2AX/MDC1 protects hairpin-sealed coding ends from CtIP resection in G1, defining a role in suppressing aberrant joining and deletions.","evidence":"H2AX-/- lymphocytes, RAG-generated DSBs, CtIP knockdown epistasis, sequencing of joins","pmids":["21160476"],"confidence":"High","gaps":["Direct mechanism by which MDC1 blocks CtIP access not structurally defined","Generality beyond V(D)J coding ends not addressed"]},{"year":2011,"claim":"Identified RNF2-BMI1 monoubiquitination at K119/120 as a prerequisite for efficient γ-H2AX formation and ATM recruitment, defining an upstream chromatin modification driving the response.","evidence":"K119/120R mutagenesis, RNF2-BMI1 Co-IP, siRNA, foci analysis after IR","pmids":["21676867"],"confidence":"High","gaps":["How K119/120 ubiquitination promotes ATM recruitment mechanistically unresolved","Interplay with RNF8/RNF168 ubiquitination not fully integrated"]},{"year":2012,"claim":"Extended H2AX into caspase-independent necroptosis by showing γ-H2AX forms an AIF/CypA DNA-degrading complex, with ATM and DNA-PK acting in temporally distinct waves.","evidence":"H2AX-/- cells, S139A/S139E rescue, ATM/DNA-PK genetic and pharmacologic interventions, AIF Co-IP","pmids":["22972376"],"confidence":"High","gaps":["Structural basis of the γH2AX-AIF-CypA complex not defined","How nuclear γ-H2AX engages AIF mechanistically unresolved"]},{"year":2012,"claim":"Proposed a feed-forward role in oxidative stress, with H2AX promoting Nox1/Rac1-driven ROS generation and cell death.","evidence":"H2AX overexpression/knockdown, Nox1 siRNA, Rac1 dominant-negative, ROS measurement, NOXA1/14-3-3ζ Co-IP","pmids":["22237206"],"confidence":"Medium","gaps":["Single-laboratory study without reconstitution","Mechanism by which a chromatin histone modulates cytoplasmic Nox1 unclear","Direct vs indirect effect on NOXA1/14-3-3ζ not resolved"]},{"year":2014,"claim":"Identified SUV39H2 methylation of K134 as a positive regulator of γ-H2AX formation, adding a methylation layer to mark control with clinical correlation.","evidence":"In vitro methyltransferase assay, K134 mutagenesis, Suv39h2 KO cells, tissue microarray","pmids":["25487737"],"confidence":"High","gaps":["Mechanistic link between K134 methylation and S139 phosphorylation not defined","Reader of K134 methylation not identified"]},{"year":2014,"claim":"Defined Dub3 as a deubiquitinase counteracting RNF8/RNF168 on H2AX, controlling 53BP1/BRCA1 focus formation and tuning the strength of the response.","evidence":"In vitro deubiquitination assay, Co-IP, RNF8/RNF168 counter-assay, catalytic-dead controls, foci analysis","pmids":["24704006"],"confidence":"High","gaps":["How Dub3 selectively spares MDC1/γH2AX foci not defined","Regulation of Dub3 recruitment to damage sites unresolved"]},{"year":2015,"claim":"Identified VRK1 as a direct Ser139 kinase that also supports histone acetylation-driven chromatin relaxation, broadening the kinase repertoire for γ-H2AX.","evidence":"In vitro kinase assay on nucleosomes, Co-IP, kinase-dead rescue, immunofluorescence","pmids":["25923214"],"confidence":"High","gaps":["Relative contribution of VRK1 versus ATM/DNA-PK in vivo not quantified","Conditions favoring VRK1 usage unresolved"]},{"year":2015,"claim":"Demonstrated that γH2AFX on asynapsed chromosomes is a causal mediator of oocyte elimination, establishing a quality-control function in meiosis.","evidence":"H2afx KO and point-mutant mice on XO background, oocyte counting, γH2AFX immunostaining","pmids":["26509888"],"confidence":"High","gaps":["Downstream effectors translating γH2AFX into oocyte death not identified","Link to apoptotic machinery in oocytes not defined"]},{"year":2016,"claim":"Showed chronic oxidative stress destabilizes H2AX via RNF168-mediated polyubiquitination and proteasomal degradation, connecting redox state to H2AX abundance.","evidence":"Co-IP, ubiquitination assays, proteasome rescue, JunD/Nrf2 manipulation in breast cancer models","pmids":["27006338"],"confidence":"Medium","gaps":["Single-laboratory study","How RNF168 switches from a stabilizer to a degrader of H2AX not reconciled with later work"]},{"year":2018,"claim":"Defined MOF/H4K16ac as required for chromatin-wide spreading of all three meiotic γH2AX waves, explaining how the mark expands beyond chromosome axes during MSCI.","evidence":"Germ-cell-specific Mof cKO mice, γH2AX and MDC1 immunostaining, RAD51 and crossover analysis","pmids":["29795555"],"confidence":"High","gaps":["Direct biochemical link between H4K16ac and γH2AX spreading not defined","Whether MOF acts identically in somatic DSB spreading not tested"]},{"year":2019,"claim":"Defined a PRMT5-RNF168-SMURF2 cascade balancing H2AX stabilization and degradation, explaining H2AX proteostasis in MTAP-deficient cancer.","evidence":"Knockdown/overexpression of PRMT5/RNF168/SMURF2, Co-IP, ubiquitination assays in glioblastoma models","pmids":["31533041"],"confidence":"Medium","gaps":["Single-laboratory study","Reconciliation of RNF168 as stabilizer here versus degrader elsewhere not addressed"]},{"year":2020,"claim":"Discovered ADP-ribosylation at Glu141 as a base-excision-repair-directing mark that recruits Neil3 and prevents erroneous DSB-factor accumulation at BER sites.","evidence":"Mass spectrometry site identification, E141A mutagenesis, Neil3 recruitment assays","pmids":["33264433"],"confidence":"High","gaps":["Enzyme depositing the E141 ADP-ribosylation not identified","Crosstalk between E141 ribosylation and S139 phosphorylation only partially defined"]},{"year":2020,"claim":"Showed chromosomal topology, not lesion identity, primarily shapes γH2AX domain landscapes, with TAD borders constraining mark spreading.","evidence":"Hi-C combined with γH2AX ChIP-seq at defined DSB sites","pmids":["32572033"],"confidence":"High","gaps":["Functional consequence of asymmetric γH2AX domains for repair not tested","Mechanism by which borders block spreading not defined"]},{"year":2020,"claim":"Identified UBE2T-RNF8 monoubiquitination of H2AX at K119/120 as a driver of CHK1 activation and radioresistance, linking the mark to checkpoint signaling.","evidence":"Co-IP, K119/120R and UBE2T C86A mutants, CHK1 chromatin fractionation, clonogenic survival and xenografts","pmids":["33087136"],"confidence":"Medium","gaps":["Single-laboratory study","Relationship to RNF2-BMI1 monoubiquitination at the same residues not reconciled"]},{"year":2021,"claim":"Linked H2AX to transcriptional activation, showing HMGA2-induced nicks trigger FACT-mediated H2AX deposition and γH2AX-dependent demethylation at TGFB1-responsive promoters.","evidence":"HMGA2 manipulation, H2AX S139 mutation, FACT assays, DNA methylation and TSS occupancy analysis","pmids":["33594057"],"confidence":"Medium","gaps":["Single-laboratory study with complex multi-step mechanism","Generality beyond TGFB1 target genes not established"]},{"year":2023,"claim":"Defined a SIRT1-H2AX axis in which Lys5 deacetylation licenses Ser139 phosphorylation, integrating acetylation control of the mark with apoptotic outcome in cardiomyocytes.","evidence":"Cardiomyocyte-specific Sirt1 cKO mice, SIRT1 manipulation in H9c2 cells, K5Q and S139A mutants, caspase-3 assay","pmids":["35258628"],"confidence":"High","gaps":["Acetyltransferase opposing SIRT1 at K5 not identified here","Mechanism by which K5 acetylation blocks S139 phosphorylation not structurally defined"]},{"year":null,"claim":"How the dense H2AX modification network (phosphorylation, acetylation, ubiquitination, methylation, ADP-ribosylation) is integrated in time and space to specify repair versus death versus checkpoint outcomes at a single lesion remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified model linking the combinatorial modification code to specific functional outputs","Conflicting roles of RNF168 as both stabilizer and degrader of H2AX not reconciled","Structural basis for reader discrimination of distinct modified tails undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[0,13,30]},{"term_id":"GO:0042393","term_label":"histone binding","supporting_discovery_ids":[9,12]},{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[3,0]}],"localization":[{"term_id":"GO:0000228","term_label":"nuclear chromosome","supporting_discovery_ids":[0,33]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,3,13]}],"pathway":[{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[0,3,13,18,22,30]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[10,24]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[21,39]},{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[17,35,37,38]},{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[8,9,16]}],"complexes":["γH2AX-AIF-CypA DNA-degrading complex"],"partners":["MDC1","ATM","DNA-PK","RNF168","FACT","AIF","EYA"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P16104","full_name":"Histone H2AX","aliases":["Histone H2A.X"],"length_aa":143,"mass_kda":15.1,"function":"Variant histone H2A which replaces conventional H2A in a subset of nucleosomes. Nucleosomes wrap and compact DNA into chromatin, limiting DNA accessibility to the cellular machineries which require DNA as a template. Histones thereby play a central role in transcription regulation, DNA repair, DNA replication and chromosomal stability. DNA accessibility is regulated via a complex set of post-translational modifications of histones, also called histone code, and nucleosome remodeling. Required for checkpoint-mediated arrest of cell cycle progression in response to low doses of ionizing radiation and for efficient repair of DNA double strand breaks (DSBs) specifically when modified by C-terminal phosphorylation","subcellular_location":"Nucleus; Chromosome","url":"https://www.uniprot.org/uniprotkb/P16104/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/H2AX","classification":"Common Essential","n_dependent_lines":861,"n_total_lines":1208,"dependency_fraction":0.7127483443708609},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"NUMA1","stoichiometry":4.0}],"url":"https://opencell.sf.czbiohub.org/search/H2AX","total_profiled":1310},"omim":[{"mim_id":"621534","title":"FAMILY WITH SEQUENCE SIMILARITY 135, MEMBER B; FAM135B","url":"https://www.omim.org/entry/621534"},{"mim_id":"621001","title":"SPERMATOGENIC FAILURE 96; SPGF96","url":"https://www.omim.org/entry/621001"},{"mim_id":"620903","title":"POLYCYSTIC KIDNEY DISEASE 8; PKD8","url":"https://www.omim.org/entry/620903"},{"mim_id":"620686","title":"PREMATURE OVARIAN FAILURE 23; POF23","url":"https://www.omim.org/entry/620686"},{"mim_id":"620610","title":"OOCYTE/ZYGOTE/EMBRYO MATURATION ARREST 21; OZEMA21","url":"https://www.omim.org/entry/620610"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Nuclear speckles","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/H2AX"},"hgnc":{"alias_symbol":[],"prev_symbol":["H2AFX"]},"alphafold":{"accession":"P16104","domains":[{"cath_id":"1.10.20.10","chopping":"17-112","consensus_level":"medium","plddt":98.2774,"start":17,"end":112}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P16104","model_url":"https://alphafold.ebi.ac.uk/files/AF-P16104-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P16104-F1-predicted_aligned_error_v6.png","plddt_mean":86.31},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=H2AX","jax_strain_url":"https://www.jax.org/strain/search?query=H2AX"},"sequence":{"accession":"P16104","fasta_url":"https://rest.uniprot.org/uniprotkb/P16104.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P16104/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P16104"}},"corpus_meta":[{"pmid":"9488723","id":"PMC_9488723","title":"DNA double-stranded breaks induce histone H2AX phosphorylation on serine 139.","date":"1998","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/9488723","citation_count":4420,"is_preprint":false},{"pmid":"11571274","id":"PMC_11571274","title":"ATM phosphorylates histone H2AX in response to DNA double-strand breaks.","date":"2001","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/11571274","citation_count":1580,"is_preprint":false},{"pmid":"18610740","id":"PMC_18610740","title":"Gamma-H2AX - a novel biomarker for DNA double-strand breaks.","date":"2008","source":"In vivo (Athens, Greece)","url":"https://pubmed.ncbi.nlm.nih.gov/18610740","citation_count":1072,"is_preprint":false},{"pmid":"18772227","id":"PMC_18772227","title":"Gamma-H2AX in recognition and signaling of DNA double-strand breaks in the context of chromatin.","date":"2008","source":"Nucleic acids 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mammalian cells and mice\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct biochemical identification of phosphorylation site by gel analysis and radiolabeling, foundational paper replicated extensively across the field\",\n      \"pmids\": [\"9488723\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"ATM is the major kinase responsible for H2AX phosphorylation at serine 139 in response to DSBs in vivo; ATM can phosphorylate H2AX in vitro; DNA-PK contributes residual phosphorylation in ATM-deficient cells, while ATR is not responsible in non-replicating cells.\",\n      \"method\": \"ATM-/- and DNA-PKcs-/- cell lines/MEFs, in vitro kinase assay, ectopic ATM reconstitution, wortmannin inhibition\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro kinase assay combined with knockout cell lines and reconstitution experiment, replicated by multiple subsequent studies\",\n      \"pmids\": [\"11571274\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"ATM and DNA-PK function redundantly to phosphorylate H2AX after ionizing radiation; ablation of both kinases is required to eliminate IR-induced H2AX phosphorylation; ATR is not required for H2AX phosphorylation by DSBs in non-replicating cells; DNA-PK-mediated H2AX phosphorylation contributes to MDC1 and 53BP1 recruitment to DSB sites.\",\n      \"method\": \"Human fibroblasts and MEFs lacking DNA-PK or ATM, LY294002 inhibition, chicken DT40 double-knockout cells\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple genetic backgrounds and pharmacological inhibition, findings replicated across cell types and organisms\",\n      \"pmids\": [\"15059890\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"γ-H2AX is not required for initial recruitment of repair/signaling proteins (Nbs1, 53BP1, Brca1) to DSBs, but is required for their subsequent accumulation and retention into irradiation-induced foci (IRIF); phosphorylation-dead H2AX mutants confirm this distinction.\",\n      \"method\": \"H2AX-/- cells reconstituted with phosphorylation mutants, immunofluorescence, live-cell imaging\",\n      \"journal\": \"Nature cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic reconstitution with phosphomutants and direct imaging, clearly separating two mechanistic steps\",\n      \"pmids\": [\"12792649\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"The INO80 ATP-dependent chromatin remodeling complex is recruited to DSBs through a direct interaction between the Nhp10 (HMG-like) subunit of INO80 and γ-H2AX (phosphorylated histone H2A in yeast); loss of Nhp10 or γ-H2AX reduces INO80 recruitment; INO80 components show synthetic genetic interactions with the RAD52 repair pathway.\",\n      \"method\": \"Co-immunoprecipitation, chromatin immunoprecipitation at HO endonuclease-induced DSB in yeast, genetic epistasis\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct biochemical interaction plus ChIP at defined DSB plus genetic epistasis, multiple orthogonal methods\",\n      \"pmids\": [\"15607974\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Protein phosphatase 2A (PP2A) catalytic subunit directly dephosphorylates γ-H2AX in vitro, co-immunoprecipitates and co-localizes with γ-H2AX in DNA damage foci; PP2A recruitment to foci is H2AX-dependent; PP2A inhibition/knockdown causes γ-H2AX foci persistence, inefficient DNA repair, and hypersensitivity to DNA damage.\",\n      \"method\": \"Co-immunoprecipitation, in vitro phosphatase assay, RNAi knockdown, immunofluorescence colocalization\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro dephosphorylation assay combined with Co-IP and functional RNAi rescue, multiple orthogonal methods in one study\",\n      \"pmids\": [\"16310392\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"A PP4 phosphatase complex (PP4C/PP4R2/PP4R3β) specifically dephosphorylates ATR-mediated γ-H2AX generated during DNA replication, acting directly on γ-H2AX within mononucleosomes in vitro; PP4 silencing causes persistence of replication-associated γ-H2AX foci and hypersensitivity to replication inhibitors but not radiomimetic drugs, indicating pathway specificity distinct from PP2A.\",\n      \"method\": \"In vitro phosphatase assay with mononucleosomes, RNAi knockdown, clonogenic survival, immunofluorescence\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with mononucleosome substrate plus RNAi functional analysis with specific pathway controls\",\n      \"pmids\": [\"18614045\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"EYA protein tyrosine phosphatase dephosphorylates a C-terminal tyrosine (Y142) of H2AX in response to genotoxic stress; when Y142 is phosphorylated, pro-apoptotic factors are recruited to the γ-H2AX tail; EYA-mediated dephosphorylation of Y142 shifts the balance toward DNA repair factor recruitment rather than apoptosis.\",\n      \"method\": \"In vitro phosphatase assay, mutation of Y142, co-immunoprecipitation, mammalian cell genotoxic stress assays\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro enzymatic assay with mutagenesis and demonstration of functional outcome (repair vs. apoptosis factor recruitment)\",\n      \"pmids\": [\"19234442\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"TIP60 histone acetyltransferase acetylates H2AX following ionizing radiation, which then promotes ubiquitination of H2AX via the ubiquitin-conjugating enzyme UBC13; this TIP60-UBC13-dependent acetylation-then-ubiquitination is required for H2AX release from damaged chromatin, enhancing histone dynamics during DNA damage response.\",\n      \"method\": \"Ionizing radiation treatment of human cells, in vitro acetylation and ubiquitination assays, immunoprecipitation, chromatin fractionation\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro enzymatic assays for both acetylation and ubiquitination, showing sequential modification and functional consequence (chromatin release)\",\n      \"pmids\": [\"17709392\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"FACT complex (Spt16/SSRP1) is an H2AX-associated factor that mediates exchange of H2AX with conventional H2A within nucleosomes; DNA-PK-mediated phosphorylation of H2AX facilitates this exchange by inducing nucleosomal conformational changes; PARP1-mediated poly-ADP-ribosylation of Spt16 inhibits FACT-dependent H2AX exchange.\",\n      \"method\": \"Purification of H2AX-associated factors, in vitro nucleosome exchange assay, DNA-PK and PARP1 activity assays\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — biochemical reconstitution of exchange reaction with purified factors, in vitro activity assays showing regulatory modifications\",\n      \"pmids\": [\"18406329\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"H2AX phosphorylation (γ-H2AX) is required for DNA ladder formation during apoptosis but not for caspase-3 activation; JNK (activated by UVA) phosphorylates H2AX; H2AX phosphorylation is critical for DNA degradation by caspase-activated DNase (CAD) in vitro; H2AX-/- MEFs lack DNA fragmentation despite normal caspase-3/CAD activation.\",\n      \"method\": \"H2AX knockout MEFs, in vitro CAD-mediated DNA degradation assay, immunofluorescence, caspase activity assays\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution of CAD-mediated DNA degradation combined with genetic knockout, multiple orthogonal methods\",\n      \"pmids\": [\"16818236\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"DNA-PK is solely responsible for H2AX phosphorylation during apoptotic DNA fragmentation, while ATM is dispensable; DNA-PKcs autophosphorylation at S2056 precedes γ-H2AX induction in apoptosis; ATM is proteolytically degraded before DNA fragmentation, leaving DNA-PK as the predominant kinase in late apoptosis.\",\n      \"method\": \"ATM-/- and DNA-PKcs-/- cell lines, pharmacological kinase inhibition, immunoblotting for autophosphorylation, immunofluorescence in apoptotic vs non-apoptotic nuclei\",\n      \"journal\": \"DNA repair\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple genetic knockouts combined with pharmacological inhibition and biochemical characterization across cell types\",\n      \"pmids\": [\"16567133\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"DNA-PK can be activated by nucleosomes (via Ku binding to ends of nucleosomal DNA) and phosphorylates H2AX within nucleosomes; histone acetylation enhances H2AX phosphorylation by DNA-PK specifically when H2AX is nucleosome-associated but not in free form.\",\n      \"method\": \"In vitro kinase assay with reconstituted nucleosomes, DNA-PK activation assay, acetylated vs non-acetylated nucleosome substrates\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with defined nucleosomal substrates, multiple modification states tested\",\n      \"pmids\": [\"14627815\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"H2AX is required for the accumulation of Nbs1, 53BP1, Brca1, and other factors into IRIF; loss of a single H2AX allele compromises genomic integrity; restoration with wild-type H2AX rescues genomic stability and radiation resistance, but substitution of the conserved serine phosphorylation site (S→A or S→E) abolishes this rescue, establishing that serine phosphorylation is functionally essential.\",\n      \"method\": \"H2AX heterozygous and homozygous null mice, gene rescue with phosphorylation-site mutants, tumor analysis, cytogenetics\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo genetic rescue with phosphomutants demonstrating mechanistic requirement, complemented by genomic instability readouts\",\n      \"pmids\": [\"12914701\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Wip1 (wild-type p53-induced phosphatase 1) directly dephosphorylates γ-H2AX in vitro and in vivo; ectopic Wip1 expression prematurely removes γ-H2AX, disrupts repair factor recruitment to damage sites, and delays DNA repair; Wip1 deletion enhances γ-H2AX in cells under oncogenic stress.\",\n      \"method\": \"In vitro phosphatase assay, ectopic expression, Wip1 deletion cells, immunofluorescence of repair foci\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct in vitro dephosphorylation plus genetic gain- and loss-of-function with functional repair readout\",\n      \"pmids\": [\"20460517\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Monoubiquitination of H2AX at Lys119/Lys120 by the RNF2-BMI1 E3 ligase complex is required for efficient γ-H2AX formation and ATM recruitment to DSBs; H2AX K120R mutation (abolishing monoubiquitination) impairs p-ATM recruitment, reduces γ-H2AX and MDC1 accumulation at DSBs, and impairs NBS1 and CHK2 activation; the regulatory effect of RNF2-BMI1 on γ-H2AX is ATM-dependent.\",\n      \"method\": \"Site-directed mutagenesis of H2AX (K119/120R), RNF2-BMI1 Co-IP, siRNA knockdown, immunofluorescence foci analysis, ionizing radiation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — mutagenesis of ubiquitination sites combined with Co-IP and functional rescue, multiple downstream pathway readouts\",\n      \"pmids\": [\"21676867\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"SUV39H2 histone methyltransferase methylates H2AX on lysine 134; mutation of K134 significantly reduces γ-H2AX levels; Suv39h2 knockout or knockdown reduces γ-H2AX after DSB induction; K134 methylation positively correlates with γ-H2AX levels in clinical tissue samples.\",\n      \"method\": \"In vitro methyltransferase assay, H2AX K134 mutagenesis, Suv39h2 KO cells, tissue microarray, clonogenic survival\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro enzymatic assay with mutagenesis and genetic knockout, replicated in clinical tissue samples\",\n      \"pmids\": [\"25487737\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"BRCA1 is required to recruit ATR to XY chromatin at the onset of meiotic sex chromosome inactivation (MSCI); ATR then phosphorylates H2AX on the sex chromosomes; in BRCA1-mutant pachytene cells, ATR mislocalizes and phosphorylates H2AX at aberrant autossomal sites, causing MSCI failure; rare cells where ATR correctly localizes to XY chromatin show H2AX phosphorylation and successful MSCI.\",\n      \"method\": \"Immunofluorescence colocalization in spermatocytes from BRCA1-mutant mice, co-staining of ATR and γH2AX\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic model with mechanistic pathway placement (BRCA1→ATR→γH2AX→MSCI) demonstrated in vivo in multiple experimental conditions\",\n      \"pmids\": [\"15589157\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Phosphorylated H2AX (γH2AX) is required for FANCD2 recruitment to chromatin at stalled replication forks; FANCD2 binding to γH2AX is BRCA1-dependent; H2AX-deficient cells display an FA-like phenotype including excess chromatid-type aberrations and MMC hypersensitivity; this hypersensitivity is not increased by additional FANCD2 depletion, placing H2AX and FANCD2 in the same pathway.\",\n      \"method\": \"H2AX knockout mouse cells, non-phosphorylable H2AX mutant (S136A/S139A), MMC sensitivity, chromatin fractionation, immunofluorescence, genetic epistasis by double depletion\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis by double depletion/knockout, phosphomutant cells, multiple orthogonal phenotypic readouts\",\n      \"pmids\": [\"17304220\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"ATM and H2AX have complementary functions; combined ATM/H2AX deficiency causes embryonic lethality and dramatic genomic instability; severe instability in double-deficient cells is associated with a requirement for H2AX in repairing oxidative DNA damage that accumulates due to ATM deficiency.\",\n      \"method\": \"ATM/H2AX double-knockout mice and MEFs, genomic instability assays, embryonic lethality analysis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic double-knockout with in vivo epistasis revealing synergistic interaction and mechanistic basis\",\n      \"pmids\": [\"18599436\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"H2AX is required for endothelial cell proliferation under hypoxic conditions; hypoxia induces replication-associated γ-H2AX in endothelial cells; H2AX deficiency reduces hypoxia-driven neovascularization in pathologic proliferative retinopathy, hind-limb ischemia, and tumor angiogenesis; endothelial-specific H2afx deletion recapitulates this phenotype.\",\n      \"method\": \"H2afx-/- mice, endothelial-specific conditional knockout, in vitro hypoxic cell proliferation assays, retinal neovascularization and tumor angiogenesis models\",\n      \"journal\": \"Nature medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — global and cell-type-specific genetic deletion with in vivo neovascularization phenotypes and in vitro mechanistic validation\",\n      \"pmids\": [\"19377486\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"H2AX is required for p21-dependent cell cycle arrest after replication stalling; in H2AX-deficient cells, p21 undergoes proteasome-dependent degradation after stalled replication, leading to mitotic catastrophe; H2AX-proficient cells increase p21 levels and arrest the cell cycle; this establishes H2AX as a component of the p53/p21 cell cycle checkpoint pathway.\",\n      \"method\": \"H2AX-/- cells and RNAi knockdown, AAV-induced stalled replication, flow cytometry, proteasome inhibitor rescue, H2AX complementation\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic and RNAi-based loss-of-function with complementation, defined molecular mechanism involving p21 stabilization\",\n      \"pmids\": [\"19273588\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"H2AX prevents CtIP-mediated DNA end resection of hairpin-sealed coding ends in G1-phase lymphocytes; γ-H2AX and its reader MDC1 inhibit CtIP access; ATM activates antagonistic pathways modulating this resection; in H2AX-deficient cells, CtIP promotes aberrant hairpin opening, leading to microhomology-mediated joins and chromosomal deletions.\",\n      \"method\": \"H2AX-/- murine lymphocytes, RAG endonuclease-generated DSB analysis, CtIP knockdown epistasis, sequencing of joins, chromosomal deletion analysis\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo genetic epistasis with CtIP and MDC1, sequencing-based characterization of repair outcomes, mechanistic pathway defined\",\n      \"pmids\": [\"21160476\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"H2AX increases ROS generation after DNA damage through the Nox1/Rac1 pathway; H2AX overexpression alone induces ROS; H2AX reduces interaction between Nox1 activator NOXA1 and its inhibitor 14-3-3ζ, thereby increasing Nox1 activity; Nox1 knockdown or Rac1N17 expression reduces H2AX-mediated ROS and cell death.\",\n      \"method\": \"H2AX overexpression/knockdown, Nox1/Nox4 siRNA, Rac1 dominant-negative expression, ROS measurement, co-immunoprecipitation of NOXA1/14-3-3ζ\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple genetic interventions and Co-IP showing mechanism, but single-laboratory study with no reconstitution\",\n      \"pmids\": [\"22237206\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"In MNNG-induced caspase-independent necroptosis, ATM and DNA-PK phosphorylate H2AX at S139 in a synergistic but temporally distinct manner (ATM early, DNA-PK later); γH2AX associates with AIF and CypA to form a DNA-degrading complex; H2AX S139A mutation or H2AX ablation abolishes chromatinolysis and necroptosis; phosphomimetic H2AX S139E rescues necroptosis in H2AX-/- cells.\",\n      \"method\": \"H2AX-/- cells, S139A/S139E mutant reconstitution, ATM/DNA-PK knockout and pharmacological inhibition, AIF co-immunoprecipitation\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout plus phosphomimetic/phospho-dead rescue, multiple kinase genetic/pharmacological interventions, mechanistic complex identified\",\n      \"pmids\": [\"22972376\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Dub3 ubiquitin hydrolase deubiquitinates H2AX; Dub3 directly interacts with H2AX and deubiquitinates it in vitro; Dub3 overexpression decreases DSB-induced H2AX monoubiquitination and abrogates 53BP1 and BRCA1 focus formation (but not MDC1/γH2AX foci); Dub3 counteracts RNF8 and RNF168 E3 ligases; Dub3 depletion accelerates H2AX dephosphorylation at later time points.\",\n      \"method\": \"In vitro deubiquitination assay, Co-immunoprecipitation, RNF8/RNF168 counter-assay, immunofluorescence foci analysis, catalytic dead mutant\",\n      \"journal\": \"Molecular oncology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro deubiquitination assay with Co-IP and functional foci readout, catalytic-dead controls\",\n      \"pmids\": [\"24704006\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Chronic oxidative stress reduces H2AX protein levels via enhanced interaction with E3 ubiquitin ligase RNF168, leading to H2AX poly-ubiquitination and proteasomal degradation; deficient JunD/Nrf2 antioxidant response drives ROS accumulation and H2AX destabilization.\",\n      \"method\": \"Co-immunoprecipitation of H2AX and RNF168, ubiquitination assays, proteasome inhibitor rescue, JunD/Nrf2 manipulation, breast cancer cell lines and patient samples\",\n      \"journal\": \"EMBO molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP and ubiquitination assays identifying mechanism, single-lab study with multiple methods\",\n      \"pmids\": [\"27006338\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"PRMT5 sustains RNF168 expression, which stabilizes H2AX protein; in the absence of RNF168 (due to PRMT5 suppression in MTAP-deficient cells), the E3 ubiquitin ligase SMURF2 destabilizes H2AX; RNF168 and SMURF2 dynamically interact with H2AX acting as stabilizer and destabilizer respectively, defining a PRMT5-RNF168-SMURF2 cascade controlling H2AX proteostasis.\",\n      \"method\": \"PRMT5/RNF168/SMURF2 knockdown and overexpression, Co-IP, ubiquitination assays, MTAP-deficient glioblastoma cell models\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP and functional knockdown in multiple cell contexts, single-laboratory study\",\n      \"pmids\": [\"31533041\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"H2AX glutamate 141 (E141) is ADP-ribosylated following oxidative DNA damage; this modification mediates recruitment of Neil3 glycosylase to DNA damage sites for base excision repair (BER); ADP-ribosylation-deficient H2AX E141A mutant enhances γH2AX (S139 phosphorylation) and erroneously accumulates DSB response factors at BER sites.\",\n      \"method\": \"Unbiased mass spectrometry identification of ADP-ribosylation site, E141A mutagenesis, Neil3 recruitment assays, comparison of BER vs DSB response factors\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — mass spectrometry identification of novel modification site combined with mutagenesis and functional recruitment assay\",\n      \"pmids\": [\"33264433\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"SIRT1 deacetylates H2AX at Lys5, and this deacetylation is required for efficient Ser139 phosphorylation of H2AX; SIRT1 knockdown increases acetyl-Lys5-H2AX and blunts γ-H2AX formation; H2AX K5Q (acetylation mimic) mutant shows reduced Ser139 phosphorylation in response to doxorubicin; K5Q and S139A mutants both enhance caspase-3 activation, demonstrating functional consequence of SIRT1-H2AX axis.\",\n      \"method\": \"Cardiomyocyte-specific Sirt1 conditional knockout mice, SIRT1 knockdown/overexpression in H9c2 cells, K5Q mutant H2AX, immunostaining for acetyl-K5 and phospho-S139 H2AX, caspase-3 assay\",\n      \"journal\": \"Cardiovascular research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo conditional knockout combined with mutagenesis of both modification sites and functional rescue, multiple orthogonal methods\",\n      \"pmids\": [\"35258628\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"H2AX controls double-strand break repair by homologous recombination (HR) between sister chromatids through interaction of γ-H2AX with the chromatin-associated adaptor protein MDC1; mass spectrometry identified novel IR-responsive post-translationally modified residues of H2AX beyond S139; HR and IR-resistance functions of H2AX are controlled largely by MDC1-interacting residues, with additional H2AX residues modulating these functions.\",\n      \"method\": \"Mass spectrometry of IR-treated cells, mutagenesis of H2AX residues, HR assay (sister chromatid recombination), clonogenic survival\",\n      \"journal\": \"Cell cycle (Georgetown, Tex.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mass spectrometry identification plus mutagenesis functional analysis, single-laboratory study\",\n      \"pmids\": [\"20703100\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"ATR deficiency leads to H2AX phosphorylation by ATM and DNA-PKcs at collapsed replication forks; increased Rad51 focal accumulation in ATR-deficient cells is largely H2AX-dependent; dual deficiency of ATR and H2AX causes synergistic increases in chromatid breaks; H2AX S139 (the ATM/DNA-PK phosphorylation site) is required for genome stabilization in the absence of ATR.\",\n      \"method\": \"ATR-deficient and H2AX-deficient cells, S139A H2AX mutant, cytogenetic analysis, Rad51 immunofluorescence, genetic double-deficiency\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic double-deficiency with phosphosite mutagenesis demonstrating epistasis and mechanism, synergistic cytogenetic phenotype\",\n      \"pmids\": [\"19049966\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"ATM-dependent H2AX phosphorylation occurs during mitosis in normally growing mammalian cells independently of exogenous DNA damage; two distinct γ-H2AX focal populations exist in unirradiated cells: large amorphous foci colocalizing with DSB repair proteins and smaller foci that do not recruit DSB repair factors; the mitotic γ-H2AX phosphorylation may contribute to fidelity of mitosis independent of DNA damage.\",\n      \"method\": \"Quantitative in situ immunofluorescence, cell cycle analysis, ATM-inhibitor treatment, multiple unirradiated mammalian cell lines\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — quantitative imaging with ATM inhibition providing mechanistic attribution, single-laboratory study\",\n      \"pmids\": [\"16030261\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Chromosomal contacts (topological structure) of a DSB site are the primary determinants of γH2AX domain landscapes; DSBs that disrupt a topological border allow γH2AX extension into both adjacent compartments; DSBs near a border produce highly asymmetric γH2AX domains with γH2AX nearly absent from one broken end.\",\n      \"method\": \"Hi-C chromosome conformation capture combined with γH2AX ChIP-seq at specific DSB sites\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genome-wide chromatin conformation combined with DSB-specific γH2AX mapping, mechanistic link between TAD structure and γH2AX spreading\",\n      \"pmids\": [\"32572033\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"VRK1 kinase directly phosphorylates H2AX at Ser139 in response to ionizing radiation; VRK1 stably interacts with H2AX and H3 under basal conditions; VRK1 depletion prevents γH2AX foci formation and reduces H3/H4 acetylation required for chromatin relaxation after DNA damage; kinase-active but not kinase-dead VRK1 rescues γH2AX foci formation.\",\n      \"method\": \"In vitro kinase assay with nucleosomal substrate, co-immunoprecipitation, VRK1 depletion/rescue with kinase-dead mutant, immunofluorescence\",\n      \"journal\": \"Epigenetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro kinase assay combined with kinase-dead mutant rescue and Co-IP, direct demonstration of VRK1 as H2AX kinase\",\n      \"pmids\": [\"25923214\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"H2AX regulates telomere clustering during meiotic prophase I; H2AX is dispensable for mitotic telomere maintenance and for chromosome fusions from critically shortened or deprotected telomeres; H2AX is required downstream of ATM for proper topological distribution of telomeres during meiosis.\",\n      \"method\": \"H2AX-/- mice, meiotic spread immunofluorescence, telomere FISH, ATM inhibitor treatment\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic knockout with specific meiotic and mitotic readouts, ATM pathway placement, single-laboratory study\",\n      \"pmids\": [\"14530383\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"HMGA2 induces DNA nicks at transcription start sites, which triggers FACT complex to incorporate H2AX-containing nucleosomes; phosphorylation of H2AX at S139 (γH2AX) is then required for repair-mediated DNA demethylation and transcription activation in the context of TGFB1 signaling.\",\n      \"method\": \"HMGA2 manipulation, H2AX S139 mutation, FACT complex assays, DNA methylation analysis, transcription start site occupancy\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple molecular interventions linking HMGA2-FACT-H2AX pathway to transcription, but single-laboratory study with complex multi-step mechanism\",\n      \"pmids\": [\"33594057\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Phosphorylated H2AFX (γH2AFX) on asynapsed chromosomes during meiotic prophase I triggers oocyte elimination at diplonema in mice with chromosome abnormalities (XO and translocations); deletion or point mutation of H2afx restores oocyte numbers in XO females to wild-type (XX) levels, establishing γH2AFX as a causal mediator of oocyte elimination.\",\n      \"method\": \"H2afx knockout and point mutant mice (XO background), oocyte counting, γH2AFX immunostaining, chromosomal asynapsis analysis\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic rescue by H2afx deletion and point mutation in defined chromosomal abnormality model, direct causal demonstration\",\n      \"pmids\": [\"26509888\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"MOF histone acetyltransferase (which generates H4K16ac) is required for the chromatin-wide expansion of all three waves of H2AX phosphorylation during male meiotic prophase I; without MOF, γH2AX signals are restricted to chromosomal axes and fail to expand to broad chromatin domains; MSCI fails in ~40% of Mof cKO pachytene cells; MOF facilitates meiotic DSB repair after RAD51 recruitment.\",\n      \"method\": \"Germ cell-specific Mof conditional knockout mice (Stra8-Cre), γH2AX immunostaining, MDC1 colocalization, RAD51 recruitment assay, crossover analysis\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo conditional knockout with multiple mechanistic readouts (γH2AX spreading, MSCI, DSB repair), defining MOF as regulator of H2AX phosphorylation expansion\",\n      \"pmids\": [\"29795555\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"UBE2T-RNF8 acts as an E2-E3 pair that monoubiquitinates H2AX/γH2AX at K119/K120 upon radiation exposure; this monoubiquitination facilitates CHK1 phosphorylation/activation and promotes CHK1 release from chromatin; mutations in UBE2T (C86A, E2-dead) or H2AX (K119/120R) abolish CHK1 activation; CHK1 inhibition impairs UBE2T-mediated radioresistance.\",\n      \"method\": \"Co-IP of UBE2T with H2AX, K119/120R H2AX mutant, C86A UBE2T mutant, CHK1 chromatin fractionation, clonogenic survival, xenograft models\",\n      \"journal\": \"Journal of experimental & clinical cancer research : CR\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mutagenesis and Co-IP with functional pathway analysis, single-laboratory study\",\n      \"pmids\": [\"33087136\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"H2AX is a histone H2A variant that, upon DNA double-strand break (DSB) formation, is rapidly phosphorylated at serine 139 (generating γ-H2AX) primarily by ATM (with redundant contributions from DNA-PK and, during replication stress, ATR and VRK1); γ-H2AX spreads over megabase chromatin domains—shaped by topological domain boundaries—and serves as a docking platform that concentrates (but is not required for initial recruitment of) DSB repair and signaling factors including MDC1, 53BP1, NBS1, and BRCA1; the modification is reversed by PP2A (at DSBs), PP4 (at replication-associated breaks), and Wip1; H2AX also undergoes additional post-translational modifications—including acetylation at K5 by TIP60 (promoting ubiquitination) and deacetylation by SIRT1 (promoting S139 phosphorylation), monoubiquitination at K119/120 by RNF2-BMI1/UBE2T-RNF8/RNF168 (counteracted by Dub3), ADP-ribosylation at E141 (for base excision repair and Neil3 recruitment), and methylation at K134 by SUV39H2 (supporting γ-H2AX formation)—that together regulate chromatin dynamics, repair factor exchange via FACT, and protein stability via PRMT5-RNF168-SMURF2; beyond DSB repair, γ-H2AX determines life/death fate via Y142 phosphorylation (directing either repair or apoptotic factor binding), participates in caspase-independent necroptosis (forming a DNA-degrading complex with AIF/CypA), is required for DNA ladder formation during apoptosis (via JNK phosphorylation enabling CAD activity), supports FANCD2 recruitment at stalled forks within the FA/BRCA pathway, activates cell cycle arrest through the p53/p21 axis, mediates meiotic sex chromosome inactivation (via ATR/BRCA1 recruitment to XY chromatin), controls meiotic telomere clustering and oocyte elimination at asynapsis, and is required for endothelial cell proliferation under hypoxia driving neovascularization.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"H2AX is a histone H2A variant that functions as the central chromatin sensor of DNA double-strand breaks (DSBs): break formation triggers rapid phosphorylation of its C-terminal Ser139 to generate \\u03b3-H2AX, marking large (~2\\u00d710^6 bp) chromatin domains around each lesion [#0]. This phosphorylation is executed primarily by ATM, with DNA-PK acting redundantly to ensure that loss of both kinases is required to eliminate the IR-induced signal [#1, #2], while VRK1 also directly phosphorylates Ser139 and supports chromatin relaxation after damage [#34]. \\u03b3-H2AX is not needed for the initial recruitment of repair/signaling factors but is required for their stable accumulation and retention in irradiation-induced foci, including NBS1, 53BP1 and BRCA1 [#3], and genetic rescue with a Ser-to-Ala/Glu mutant fails to restore genomic stability, establishing Ser139 phosphorylation as functionally essential [#13]. The mark spreads across chromatin in a manner dictated by topological domain boundaries [#33] and acts through the reader MDC1 to direct homologous recombination between sister chromatids [#30], to protect coding-end hairpins from CtIP-mediated resection [#22], and to recruit FANCD2 at stalled forks within the FA/BRCA pathway [#18]; in the absence of ATR, ATM/DNA-PK-dependent Ser139 phosphorylation stabilizes collapsed replication forks [#31]. The signal is reversed by distinct phosphatases acting on different lesion contexts: PP2A at DSBs [#5], the PP4C/PP4R2/PP4R3\\u03b2 complex at replication-associated breaks [#6], Wip1 to terminate the response [#14], and EYA, which dephosphorylates the C-terminal Tyr142 to shift \\u03b3-H2AX from apoptotic to repair-factor binding [#7]. Beyond phosphorylation, H2AX is regulated by an extensive modification network: TIP60-UBC13 acetylation-then-ubiquitination drives H2AX release from chromatin [#8], FACT mediates H2AX/H2A nucleosome exchange in a phosphorylation- and PARP1-regulated manner [#9], SIRT1 deacetylates Lys5 to permit Ser139 phosphorylation [#29], RNF2-BMI1 monoubiquitination at K119/120 and SUV39H2 methylation at K134 promote \\u03b3-H2AX formation [#15, #16], UBE2T-RNF8 monoubiquitination links \\u03b3-H2AX to CHK1 activation [#39], ADP-ribosylation at Glu141 directs Neil3 recruitment for base excision repair [#28], and a PRMT5-RNF168-SMURF2 axis with the deubiquitinase Dub3 governs H2AX proteostasis and repair-factor focus formation [#25, #27]. H2AX activity extends beyond repair to cell-fate decisions, being required for p21-dependent cell-cycle arrest [#21], DNA-ladder formation during apoptosis via JNK and CAD [#10], and assembly of an AIF/CypA DNA-degrading complex in caspase-independent necroptosis [#24]. In the germline, H2AX phosphorylation mediates meiotic sex chromosome inactivation downstream of BRCA1/ATR [#17], controls meiotic telomere clustering [#35], and drives oocyte elimination at asynapsis [#37], with MOF-dependent H4K16 acetylation enabling chromatin-wide \\u03b3-H2AX spreading in meiosis [#38]; it is additionally required for hypoxia-driven endothelial proliferation and neovascularization [#20].\",\n  \"teleology\": [\n    {\n      \"year\": 1998,\n      \"claim\": \"Established that DSBs are physically signaled in chromatin by a specific histone modification, defining \\u03b3-H2AX as a megabase-scale break marker.\",\n      \"evidence\": \"2D gel electrophoresis with 32P incorporation after in vivo irradiation of mammalian cells and mice\",\n      \"pmids\": [\"9488723\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify the responsible kinase\", \"Did not establish the functional consequence of the modification\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Identified ATM as the major Ser139 kinase with DNA-PK as a backup, answering which signaling kinase couples break detection to the chromatin mark.\",\n      \"evidence\": \"ATM-/- and DNA-PKcs-/- cells, in vitro kinase assay, reconstitution and wortmannin inhibition\",\n      \"pmids\": [\"11571274\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative contribution of each kinase at different lesion types not fully resolved\", \"Did not address replication-stress kinases\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Distinguished initial factor recruitment from stable focus accumulation, showing \\u03b3-H2AX is a retention/amplification platform rather than the primary recruitment signal.\",\n      \"evidence\": \"H2AX-/- cells reconstituted with phosphomutants, immunofluorescence and live imaging; phosphomutant rescue in null mice\",\n      \"pmids\": [\"12792649\", \"12914701\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which retained factors execute repair not defined\", \"Reader proteins bridging \\u03b3-H2AX to factors not yet identified\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Connected \\u03b3-H2AX to chromatin remodeling by showing direct recruitment of the INO80 complex, beginning the mechanistic picture of how the mark reshapes chromatin at breaks.\",\n      \"evidence\": \"Co-IP, ChIP at HO-induced DSB and genetic epistasis in yeast\",\n      \"pmids\": [\"15607974\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Conservation of the Nhp10-\\u03b3H2A interaction to mammals not established here\", \"Functional outcome of remodeling on repair pathway choice unresolved\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Resolved kinase redundancy by showing combined ATM/DNA-PK loss is required to abolish IR-induced phosphorylation and that DNA-PK contributes to MDC1/53BP1 recruitment.\",\n      \"evidence\": \"Human fibroblasts/MEFs lacking ATM or DNA-PK, LY294002 inhibition, DT40 double-knockouts\",\n      \"pmids\": [\"15059890\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not address ATR contribution during replication\", \"Spatial division of labor between kinases at a single break not mapped\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Identified PP2A as the DSB-associated eraser, establishing that the \\u03b3-H2AX signal is actively reversed to permit repair completion.\",\n      \"evidence\": \"In vitro phosphatase assay, Co-IP, colocalization and RNAi with repair/survival readouts\",\n      \"pmids\": [\"16310392\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not distinguish lesion-context specificity from other phosphatases\", \"Regulation of PP2A recruitment timing unresolved\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Showed DNA-PK can be activated by and phosphorylate H2AX within nucleosomes, and that acetylation enhances this only in the nucleosomal context, linking chromatin state to mark deposition.\",\n      \"evidence\": \"In vitro kinase assays with reconstituted, acetylated/non-acetylated nucleosomes\",\n      \"pmids\": [\"14627815\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo relevance of acetylation-stimulated phosphorylation not tested here\", \"Identity of the acetyltransferase not addressed\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Defined a repair-independent role for \\u03b3-H2AX in apoptotic DNA fragmentation, showing it is required for CAD-mediated DNA laddering downstream of JNK.\",\n      \"evidence\": \"H2AX-/- MEFs, in vitro CAD degradation assay, caspase activity assays\",\n      \"pmids\": [\"16818236\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How \\u03b3-H2AX enables CAD access to DNA not structurally defined\", \"Generality across apoptotic stimuli not fully tested\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Showed that in late apoptosis DNA-PK, not ATM (which is degraded), drives \\u03b3-H2AX, refining kinase usage by cellular context.\",\n      \"evidence\": \"ATM-/- and DNA-PKcs-/- cells, kinase inhibition, autophosphorylation immunoblot\",\n      \"pmids\": [\"16567133\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Trigger for DNA-PK activation in apoptotic chromatin not defined\", \"Link to the CAD fragmentation step not mechanistically bridged\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Placed H2AX in the FA/BRCA pathway by showing \\u03b3-H2AX is required for BRCA1-dependent FANCD2 recruitment at stalled forks, extending its role to replication stress.\",\n      \"evidence\": \"H2AX-null cells, phosphomutant, MMC sensitivity, chromatin fractionation and double-depletion epistasis\",\n      \"pmids\": [\"17304220\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct physical \\u03b3H2AX-FANCD2 contact vs indirect not resolved\", \"Reader linking \\u03b3-H2AX to FANCD2 not identified\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Established acetylation-coupled ubiquitination by TIP60-UBC13 as the mechanism for H2AX release from damaged chromatin, adding histone dynamics to the response.\",\n      \"evidence\": \"In vitro acetylation and ubiquitination assays, chromatin fractionation after IR\",\n      \"pmids\": [\"17709392\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Acetylated lysine residue not specified here\", \"Downstream fate of released H2AX not tracked\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Identified the FACT complex as the machine that exchanges H2AX in nucleosomes, with phosphorylation promoting and PARP1-ribosylation inhibiting exchange, defining mark turnover dynamics.\",\n      \"evidence\": \"Purification of H2AX-associated factors, in vitro nucleosome exchange, DNA-PK and PARP1 activity assays\",\n      \"pmids\": [\"18406329\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo contribution of FACT exchange to repair outcome not quantified\", \"Coordination with INO80 remodeling not addressed\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Defined a replication-specific eraser, the PP4C/PP4R2/PP4R3\\u03b2 complex, distinguishing erasure of ATR-generated \\u03b3-H2AX from PP2A action at DSBs.\",\n      \"evidence\": \"In vitro phosphatase assay on mononucleosomes, RNAi, clonogenic survival with pathway-specific drugs\",\n      \"pmids\": [\"18614045\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Recruitment mechanism of PP4 to replication foci unresolved\", \"Crosstalk with PP2A/Wip1 not mapped\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Demonstrated that H2AX stabilizes collapsed forks in ATR-deficient cells via ATM/DNA-PK Ser139 phosphorylation, integrating H2AX into the replication-stress response.\",\n      \"evidence\": \"ATR/H2AX double-deficient cells, S139A mutant, cytogenetics, Rad51 immunofluorescence\",\n      \"pmids\": [\"19049966\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How \\u03b3-H2AX promotes Rad51 loading mechanistically unresolved\", \"Direct vs indirect fork protection not distinguished\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Revealed a checkpoint role by showing H2AX is required to stabilize p21 and enforce cell-cycle arrest after replication stalling, preventing mitotic catastrophe.\",\n      \"evidence\": \"H2AX-/- cells and RNAi, AAV-induced stalling, flow cytometry, proteasome rescue, complementation\",\n      \"pmids\": [\"19273588\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular link from \\u03b3-H2AX chromatin to p21 stabilization not defined\", \"Role of p53 upstream of p21 in this context not dissected\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Showed ATM and H2AX have complementary essential roles, with H2AX required to repair oxidative damage accumulating in ATM deficiency, explaining their synthetic lethality.\",\n      \"evidence\": \"ATM/H2AX double-knockout mice and MEFs, genomic instability and embryonic lethality analysis\",\n      \"pmids\": [\"18599436\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct biochemical role of H2AX in oxidative damage repair not defined\", \"Pathway connecting H2AX to oxidative lesion repair unresolved\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Uncovered a life/death switch at the C-terminal tail, where EYA dephosphorylation of Tyr142 biases between apoptotic and repair factor binding to \\u03b3-H2AX.\",\n      \"evidence\": \"In vitro phosphatase assay, Y142 mutagenesis, Co-IP, genotoxic stress assays\",\n      \"pmids\": [\"19234442\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the Y142 kinase not addressed here\", \"Specific apoptotic factors recruited not fully enumerated\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Added Wip1 as a phosphatase that terminates the \\u03b3-H2AX response, linking the mark's erasure to oncogenic-stress regulation.\",\n      \"evidence\": \"In vitro phosphatase assay, ectopic expression and Wip1 deletion, repair foci imaging\",\n      \"pmids\": [\"20460517\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Lesion-context specificity relative to PP2A/PP4 not defined\", \"Recruitment of Wip1 to foci not characterized\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Established MDC1-interacting residues of H2AX as the principal determinant of sister-chromatid HR and IR resistance, mapping the reader-dependent output of the mark.\",\n      \"evidence\": \"Mass spectrometry of IR-treated cells, H2AX residue mutagenesis, HR and clonogenic assays\",\n      \"pmids\": [\"20703100\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-laboratory study without independent replication\", \"Functions of additional modified residues only partially defined\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Showed \\u03b3-H2AX/MDC1 protects hairpin-sealed coding ends from CtIP resection in G1, defining a role in suppressing aberrant joining and deletions.\",\n      \"evidence\": \"H2AX-/- lymphocytes, RAG-generated DSBs, CtIP knockdown epistasis, sequencing of joins\",\n      \"pmids\": [\"21160476\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct mechanism by which MDC1 blocks CtIP access not structurally defined\", \"Generality beyond V(D)J coding ends not addressed\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Identified RNF2-BMI1 monoubiquitination at K119/120 as a prerequisite for efficient \\u03b3-H2AX formation and ATM recruitment, defining an upstream chromatin modification driving the response.\",\n      \"evidence\": \"K119/120R mutagenesis, RNF2-BMI1 Co-IP, siRNA, foci analysis after IR\",\n      \"pmids\": [\"21676867\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How K119/120 ubiquitination promotes ATM recruitment mechanistically unresolved\", \"Interplay with RNF8/RNF168 ubiquitination not fully integrated\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Extended H2AX into caspase-independent necroptosis by showing \\u03b3-H2AX forms an AIF/CypA DNA-degrading complex, with ATM and DNA-PK acting in temporally distinct waves.\",\n      \"evidence\": \"H2AX-/- cells, S139A/S139E rescue, ATM/DNA-PK genetic and pharmacologic interventions, AIF Co-IP\",\n      \"pmids\": [\"22972376\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of the \\u03b3H2AX-AIF-CypA complex not defined\", \"How nuclear \\u03b3-H2AX engages AIF mechanistically unresolved\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Proposed a feed-forward role in oxidative stress, with H2AX promoting Nox1/Rac1-driven ROS generation and cell death.\",\n      \"evidence\": \"H2AX overexpression/knockdown, Nox1 siRNA, Rac1 dominant-negative, ROS measurement, NOXA1/14-3-3\\u03b6 Co-IP\",\n      \"pmids\": [\"22237206\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-laboratory study without reconstitution\", \"Mechanism by which a chromatin histone modulates cytoplasmic Nox1 unclear\", \"Direct vs indirect effect on NOXA1/14-3-3\\u03b6 not resolved\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Identified SUV39H2 methylation of K134 as a positive regulator of \\u03b3-H2AX formation, adding a methylation layer to mark control with clinical correlation.\",\n      \"evidence\": \"In vitro methyltransferase assay, K134 mutagenesis, Suv39h2 KO cells, tissue microarray\",\n      \"pmids\": [\"25487737\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanistic link between K134 methylation and S139 phosphorylation not defined\", \"Reader of K134 methylation not identified\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Defined Dub3 as a deubiquitinase counteracting RNF8/RNF168 on H2AX, controlling 53BP1/BRCA1 focus formation and tuning the strength of the response.\",\n      \"evidence\": \"In vitro deubiquitination assay, Co-IP, RNF8/RNF168 counter-assay, catalytic-dead controls, foci analysis\",\n      \"pmids\": [\"24704006\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How Dub3 selectively spares MDC1/\\u03b3H2AX foci not defined\", \"Regulation of Dub3 recruitment to damage sites unresolved\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Identified VRK1 as a direct Ser139 kinase that also supports histone acetylation-driven chromatin relaxation, broadening the kinase repertoire for \\u03b3-H2AX.\",\n      \"evidence\": \"In vitro kinase assay on nucleosomes, Co-IP, kinase-dead rescue, immunofluorescence\",\n      \"pmids\": [\"25923214\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative contribution of VRK1 versus ATM/DNA-PK in vivo not quantified\", \"Conditions favoring VRK1 usage unresolved\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Demonstrated that \\u03b3H2AFX on asynapsed chromosomes is a causal mediator of oocyte elimination, establishing a quality-control function in meiosis.\",\n      \"evidence\": \"H2afx KO and point-mutant mice on XO background, oocyte counting, \\u03b3H2AFX immunostaining\",\n      \"pmids\": [\"26509888\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream effectors translating \\u03b3H2AFX into oocyte death not identified\", \"Link to apoptotic machinery in oocytes not defined\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Showed chronic oxidative stress destabilizes H2AX via RNF168-mediated polyubiquitination and proteasomal degradation, connecting redox state to H2AX abundance.\",\n      \"evidence\": \"Co-IP, ubiquitination assays, proteasome rescue, JunD/Nrf2 manipulation in breast cancer models\",\n      \"pmids\": [\"27006338\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-laboratory study\", \"How RNF168 switches from a stabilizer to a degrader of H2AX not reconciled with later work\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Defined MOF/H4K16ac as required for chromatin-wide spreading of all three meiotic \\u03b3H2AX waves, explaining how the mark expands beyond chromosome axes during MSCI.\",\n      \"evidence\": \"Germ-cell-specific Mof cKO mice, \\u03b3H2AX and MDC1 immunostaining, RAD51 and crossover analysis\",\n      \"pmids\": [\"29795555\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct biochemical link between H4K16ac and \\u03b3H2AX spreading not defined\", \"Whether MOF acts identically in somatic DSB spreading not tested\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Defined a PRMT5-RNF168-SMURF2 cascade balancing H2AX stabilization and degradation, explaining H2AX proteostasis in MTAP-deficient cancer.\",\n      \"evidence\": \"Knockdown/overexpression of PRMT5/RNF168/SMURF2, Co-IP, ubiquitination assays in glioblastoma models\",\n      \"pmids\": [\"31533041\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-laboratory study\", \"Reconciliation of RNF168 as stabilizer here versus degrader elsewhere not addressed\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Discovered ADP-ribosylation at Glu141 as a base-excision-repair-directing mark that recruits Neil3 and prevents erroneous DSB-factor accumulation at BER sites.\",\n      \"evidence\": \"Mass spectrometry site identification, E141A mutagenesis, Neil3 recruitment assays\",\n      \"pmids\": [\"33264433\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Enzyme depositing the E141 ADP-ribosylation not identified\", \"Crosstalk between E141 ribosylation and S139 phosphorylation only partially defined\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Showed chromosomal topology, not lesion identity, primarily shapes \\u03b3H2AX domain landscapes, with TAD borders constraining mark spreading.\",\n      \"evidence\": \"Hi-C combined with \\u03b3H2AX ChIP-seq at defined DSB sites\",\n      \"pmids\": [\"32572033\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of asymmetric \\u03b3H2AX domains for repair not tested\", \"Mechanism by which borders block spreading not defined\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Identified UBE2T-RNF8 monoubiquitination of H2AX at K119/120 as a driver of CHK1 activation and radioresistance, linking the mark to checkpoint signaling.\",\n      \"evidence\": \"Co-IP, K119/120R and UBE2T C86A mutants, CHK1 chromatin fractionation, clonogenic survival and xenografts\",\n      \"pmids\": [\"33087136\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-laboratory study\", \"Relationship to RNF2-BMI1 monoubiquitination at the same residues not reconciled\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Linked H2AX to transcriptional activation, showing HMGA2-induced nicks trigger FACT-mediated H2AX deposition and \\u03b3H2AX-dependent demethylation at TGFB1-responsive promoters.\",\n      \"evidence\": \"HMGA2 manipulation, H2AX S139 mutation, FACT assays, DNA methylation and TSS occupancy analysis\",\n      \"pmids\": [\"33594057\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-laboratory study with complex multi-step mechanism\", \"Generality beyond TGFB1 target genes not established\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Defined a SIRT1-H2AX axis in which Lys5 deacetylation licenses Ser139 phosphorylation, integrating acetylation control of the mark with apoptotic outcome in cardiomyocytes.\",\n      \"evidence\": \"Cardiomyocyte-specific Sirt1 cKO mice, SIRT1 manipulation in H9c2 cells, K5Q and S139A mutants, caspase-3 assay\",\n      \"pmids\": [\"35258628\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Acetyltransferase opposing SIRT1 at K5 not identified here\", \"Mechanism by which K5 acetylation blocks S139 phosphorylation not structurally defined\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the dense H2AX modification network (phosphorylation, acetylation, ubiquitination, methylation, ADP-ribosylation) is integrated in time and space to specify repair versus death versus checkpoint outcomes at a single lesion remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified model linking the combinatorial modification code to specific functional outputs\", \"Conflicting roles of RNF168 as both stabilizer and degrader of H2AX not reconciled\", \"Structural basis for reader discrimination of distinct modified tails undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [0, 13, 30]},\n      {\"term_id\": \"GO:0042393\", \"supporting_discovery_ids\": [9, 12]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [3, 0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0000228\", \"supporting_discovery_ids\": [0, 33]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 3, 13]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [0, 3, 13, 18, 22, 30]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [10, 24]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [21, 39]},\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [17, 35, 37, 38]},\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [8, 9, 16]}\n    ],\n    \"complexes\": [\"\\u03b3H2AX-AIF-CypA DNA-degrading complex\"],\n    \"partners\": [\"MDC1\", \"MDC1\", \"ATM\", \"DNA-PK\", \"RNF168\", \"FACT\", \"AIF\", \"EYA\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}